Sunday, May 1, 2016

Audio system for cooler finished


A couple of weeks ago I started to make a tiny audio system for our cooler. In my previous blogpost I described all the audio components that I chose for this project. I wanted the components to be small since I didn't want to waste too much space in the cooler. With the audio components in hand I could design other parts for the audio system. I needed an enclosure for most of the audio components and a simple console to operate the audio. The parts were 3d printed with my Hephestos 2.

The complete audio system in the lid of the cooler. Most components are placed in the 3d printed enclosure.

The enclosure for the amplifier

While designing I borrowed heavily from Adafruits Trinket Neopixel led longboard, a project that upgrades a longboard with Neopixel LEDs. The battery, amplifier and Powerboost 500c had to fit into a small enclosure for protection. The enclosure needed several rectangular cavities for a switch, micro usb and wires.

Enclosure (bottom and lid) for the battery, amplifier and Powerboost 500c designed in FreeCAD.
The Powerboost 500c and the amplifier are screwed directly to the lid of the 3d printed enclosure while the Li polymer battery is pressed to the bottom by a PLA strip.

Kemo 3.5W Amplifier and Adafruit Powerboost 500c are screwed directly to the lid of the 3d printed enclosure. The battery is placed firmly under a PLA strip.
In the front the enclosure with the Powerboost and amplifier screwed to the lid. On top of the enclosure is the lock.

Attaching the enclosure to the cooler lid

I needed a simple design to attach the enclosure firmly to the inside of the cooler lid but I also wanted to be able to slide the enclosure out and back in again if necessary. Again I took an idea from the Adafruit Trinket Neopixel LED longboard . I designed a slide lock that consists of two pieces a mount and a lock. The lock slides into the mount until the stop on the lock reaches the mount.

The lock fits into the mount but can be slided in and out. Two two holes in the lock are used to screw the lock to the enclosure.

The console

I also needed some kind of console to operate the audio system. I decided to keep it simple with a 3.5mm audio plug and volume control. The on/off switch is in the enclosure (for now).

Back side of the console with the 3.5mm audio plug for audio-in and 10K potentiometer for volume control.

Preparing the cooler

Preparing the cooler is pretty straightforward. First I drilled a circular hole in the top of the lid just wide enough (68mm) for the speaker. This hole is centered on the top. Next I cut with my Dremel a rectangular hole in the side of the lid just wide enough for the console to fit. With these two holes the cooler lid was ready and all components could be attached. The speaker was screwed onto the lid while the console and the mount were glued to the lid. Glueing proved to be difficult. I tried  two-component expoxy and superglue (cyanoacrylate base) for glueing the enclosure to the cooler lid but the enclosure came loose in both events. Next I tried double-sided tape and this works however time will tell if it is a lasting solution. With most of the work done it is time to test my audio enabled cooler. Which some nice weather coming up I'll test the cooler outside and report back the results.

Circular hole in the center of the lid for the speaker to fit in.
The finished products. In the upcoming month I'll see how it performs.

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